[英]Fetching information from server and assign required data to Spinner using Retrofit
[英]show progress bar before fetching data from server using retrofit
我正在使用改造、协程、livedata、mvvm 开发在线购物应用程序...
我想在从服务器获取数据几秒钟之前显示进度条
如果我有一个 api 请求,我可以显示,但在这个应用程序中,我有多个请求
在这种情况下我应该怎么做我应该如何显示进度条?
接口服务
@GET("homeslider.php")
suspend fun getSliderImages(): Response<List<Model.Slider>>
@GET("amazingoffer.php")
suspend fun getAmazingProduct(): Response<List<Model.AmazingProduct>>
@GET("handsImages.php")
suspend fun getHandsFreeData(
@Query(
"handsfree_id"
) handsfree_id: Int
): Response<List<Model.HandsFreeImages>>
@GET("handsfreemoreinfo.php")
suspend fun gethandsfreemoreinfo(): Response<List<Model.HandsFreeMore>>
@GET("wristmetadata.php")
suspend fun getWristWatchMetaData(
@Query(
"wrist_id"
) wrist_id: Int
): Response<List<Model.WristWatch>>
存储库
fun getSliderImages(): LiveData<List<Model.Slider>> {
val data = MutableLiveData<List<Model.Slider>>()
val job = Job()
applicationScope.launch(IO + job) {
val response = api.getSliderImages()
withContext(Main + SupervisorJob(job)) {
data.value = response.body()
}
job.complete()
job.cancel()
}
return data
}
fun getAmazingOffer(): LiveData<List<Model.AmazingProduct>> {
val data = MutableLiveData<List<Model.AmazingProduct>>()
val job = Job()
applicationScope.launch(IO + job) {
val response = api.getAmazingProduct()
withContext(Main + SupervisorJob(job)) {
data.value = response.body()
}
job.complete()
job.cancel()
}
return data
}
fun getHandsFreeData(handsree_id: Int): LiveData<List<Model.HandsFreeImages>> {
val dfData = MutableLiveData<List<Model.HandsFreeImages>>()
val job = Job()
applicationScope.launch(IO + job) {
val response = api.getHandsFreeData(handsree_id)
withContext(Main + SupervisorJob(job)) {
dfData.value = response.body()
}
job.complete()
job.cancel()
}
return dfData
}
fun getHandsFreeMore(): LiveData<List<Model.HandsFreeMore>> {
val data = MutableLiveData<List<Model.HandsFreeMore>>()
val job = Job()
applicationScope.launch(IO + job) {
val response = api.gethandsfreemoreinfo()
withContext(Main + SupervisorJob(job)) {
data.value = response.body()
}
job.complete()
job.cancel()
}
return data
}
视图模型
fun getSliderImages() = repository.getSliderImages()
fun getAmazingOffer() = repository.getAmazingOffer()
fun recieveAdvertise() = repository.recieveAdvertise()
fun dailyShoes(context: Context) = repository.getDailyShoes(context)
我会感谢你的帮助
我不禁注意到您的存储库包含大量重复代码。 这里要学习的第一点是Repository
中的所有逻辑,它通常在ViewModel
。 第二件事是您正在使用applicationScope
来启动您的coroutines
,这通常是使用viewModelScope
(负责取消)对象完成的,该对象在每个viewModel
可用。
所以首先我们必须处理那些重复的代码并将其移动到ViewModel
。 所以你的 viewModel 现在看起来像
class YourViewModel: ViewModel() {
// Your other init code, repo creation etc
// Live data objects for progressBar and error, we will observe these in Fragment/Activity
val showProgress: MutableLiveData<Boolean> = MutableLiveData()
val errorMessage: MutableLiveData<String> = MutableLiveData()
/**
* A Generic api caller, which updates the given live data object with the api result
* and internally takes care of progress bar visibility. */
private fun <T> callApiAndPost(liveData: MutableLiveData<T>,
apiCall: () -> Response<T> ) = viewModelScope.launch {
try{
showProgress.postValue(true) // Show prgress bar when api call is active
if(result.code() == 200) { liveData.postValue(result.body()) }
else{ errorMessage.postValue("Network call failed, try again") }
showProgress.postValue(false)
}
catch (e: Exception){
errorMessage.postValue("Network call failed, try again")
showProgress.postValue(false)
}
}
/******** Now all your API call methods should be called as *************/
// First declare the live data object which will contain the api result
val sliderData: MutableLiveData<List<Model.Slider>> = MutableLiveData()
// Now call the API as
fun getSliderImages() = callApiAndPost(sliderData) {
repository.getSliderImages()
}
}
之后从Repository
中删除所有逻辑并使其简单地调用网络方法
suspend fun getSliderImages() = api.getSliderImages() // simply delegate to network layer
最后要显示进度条,只需将Activity
/ Fragment
的showProgress
LiveData
对象观察为
viewModel.showProgress.observer(this, Observer{
progressBar.visibility = if(it) View.VISIBLE else View.GONE
}
首先创建一个枚举类状态:
enum class Status {
SUCCESS,
ERROR,
LOADING
}
然后像这样创建资源类:
data class Resource<out T>(val status: Status, val data: T?, val message: String?) {
companion object {
fun <T> success(data: T?): Resource<T> {
return Resource(Status.SUCCESS, data, null)
}
fun <T> error(msg: String, data: T?): Resource<T> {
return Resource(Status.ERROR, data, msg)
}
fun <T> loading(data: T?): Resource<T> {
return Resource(Status.LOADING, data, null)
}
}
}
现在将您的请求添加到响应列表中:
var list = java.util.ArrayList<Response<*>>()
suspend fun getApis() = list.addAll(
listOf(
api.advertise(),
api.getAmazingProduct(),
api.dailyShoes(),
api.getSliderImages(),
.
.
.
)
)
在您的视图模型类中:
private val _apis = MutableLiveData<Resource<*>>()
val apis: LiveData<Resource<*>>
get() = _apis
init {
getAllApi()
}
fun getAllApi() {
val job = Job()
viewModelScope.launch(IO + job) {
_apis.postValue(
Resource.loading(null)
)
delay(2000)
repository.getApis().let {
withContext(Main + SupervisorJob(job)) {
it.let {
if (it) {
_apis.postValue(Resource.success(it))
} else {
_apis.postValue(Resource.error("Unknown error eccured", null))
}
}
}
}
job.complete()
job.cancel()
}
}
现在您可以使用 status 来显示这样的进度。 在您的目标片段中使用此部分:
private fun setProgress() {
viewModel.apis.observe(viewLifecycleOwner) {
when (it.status) {
Status.SUCCESS -> {
binding.apply {
progress.visibility = View.INVISIBLE
line1.visibility = View.VISIBLE
parentscroll.visibility = View.VISIBLE
}
}
Status.ERROR -> {
binding.apply {
progress.visibility = View.INVISIBLE
line1.visibility = View.INVISIBLE
parentscroll.visibility = View.INVISIBLE
}
}
Status.LOADING -> {
binding.apply {
progress.visibility = View.VISIBLE
line1.visibility = View.INVISIBLE
parentscroll.visibility = View.INVISIBLE
}
}
}
}
}
希望对你有帮助。
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